The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque and thereby accelerates a vehicle. Additionally or alternatively, an electric motor may be used to produce drive torque and thereby accelerate the vehicle. The amount of drive torque produced is based on a driver input such as the position of an accelerator pedal or a cruise control setting. An engine control system typically stores multiple mappings of the driver input to a desired torque and determines a driver torque request based on a selected one of the mappings. The engine control system may then generate a torque command based on the driver torque request and other torque requests, and use the torque command to control the amount of drive torque produced. The other torque requests may include torque requests generated to compensate for accessory loads, to facilitate a transmission shift, and/or to assist with traction control.
In some instances, the amount of drive torque produced may result in vehicle acceleration that is different than desired. The difference between the desired vehicle acceleration and the actual vehicle acceleration may be referred to as a vehicle acceleration delta. Some engine control systems may determine a desired torque based on the driver torque request and the other torque requests in parallel with generating the torque command. The engine control systems may then determine a difference between the desired torque and the torque command and compare the difference to a threshold torque, which may be predetermined through calibration. If the difference is greater than the threshold torque and the vehicle acceleration delta is greater than desired, the engine control systems may shut off an engine to decrease the vehicle acceleration delta. Evaluating the torque command using a threshold torque to decrease the vehicle acceleration delta adds cost and complexity. In addition, shutting off the engine may be undesired in certain situations and may result in undesired cost and inconvenience to the driver.